This invention relates to clevis hangers for supporting cable, conduit and pipe from a ceiling or other overhead support.
Conduit installed along ceilings and the like is often supported by a series of clevis hangers connected to support rods depending from the ceiling. Each clevis hanger typically includes a lower U-shaped hanger member for supporting the conduit and an upper hanger member for connecting the clevis hanger to the support rod. The lower and upper hanger members include arms having openings which, when horizontally aligned, receive a fastener to connect the two members together. In one method of assembling the clevis hanger and installing the conduit, the lower U-shaped hanger member is fitted onto the conduit and raised with the conduit above an installer's head to mate with the upper hanger member which is already connected to the support rod. Due to the poor lighting conditions and unfavorable position of the installer with respect to the clevis hanger, it is usually difficult for the installer to align the openings of the lower and upper hanger members so that the fastener may be inserted through the openings to connect the two members together.
In another installation method, the lower hanger member is connected to the upper hanger member and the clevis hanger assembly is connected to the support rod. The conduit is then fed through the clevis hanger. Since the lower hanger member is typically free to rotate about a longitudinal axis extending through the fastener, the conduit often causes the lower hanger member to rotate away from the conduit as the conduit contacts the lower hanger member. This is particularly a problem when a conduit is fed through the clevis hanger at an angle from a location below the clevis hanger. As the lower hanger member rotates away from its conduit supporting position, the opening through which the conduit is fed is reduced, thus making it difficult to push the conduit through the clevis hanger without manually holding the lower hanger member in its conduit supporting position. Furthermore, as the conduit is fed through the clevis hanger, rotation of the lower hanger member causes a sharp outer edge of the lower hanger member to scrape against the conduit. The scraping of the outer edge of the lower hanger member along the conduit as it is fed through the clevis hanger not only damages a conduit formed from a plastic material, it makes installation more difficult and puts additional stress on the support rod. The rotation of the lower member also makes adjustment of the clevis hanger to support a conduit at a specific height and angle difficult due to the variability in height caused by the angled position of the lower hanger member.
Moreover, since the inside surface of the lower hanger member of the clevis hanger typically conforms to the outer periphery of the conduit, condensation often builds up and is trapped between the conduit and clevis hanger which may damage the clevis hanger or conduit over time. The surface contact between the pipe and clevis hanger also makes installation more difficult due to friction between the pipe and clevis hanger, and makes it difficult for the conduit to move within the lower hanger for adjustment due to expansion and contraction of the conduit.
Furthermore, in order to reduce weight and cost of the clevis hanger, the lower hanger member is typically formed from a thin strap of metal. The thin metal strap often loses its shape over time and is easily bent and damaged due to its lack of stiffness.
Accordingly, there is presently a need for a clevis hanger which allows for easy non-visual alignment between the lower and upper hanger members to facilitate assembly of the clevis hanger, a clevis hanger which limits rotation of the lower hanger member about the fastener to facilitate feeding of the conduit through the clevis hanger, a clevis hanger with increased stiffening of the lower member to provide a rigid lightweight clevis hanger, and a clevis hanger which reduces the contact surface area between the lower hanger member and conduit to eliminate buildup of condensation, prevent damage to the conduit by an outer edge of the lower hanger member and further facilitate installation of the conduit through the clevis hanger.